/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.testutils;

import org.apache.flink.runtime.execution.Environment;
import org.apache.flink.runtime.jobgraph.tasks.AbstractInvokable;

import java.util.concurrent.CompletableFuture;
import java.util.concurrent.Future;

/**
 * An {@link AbstractInvokable} that blocks at some point until cancelled.
 *
 * <p>Subclasses typically call the {@link #waitUntilCancelled()} method somewhere in their {@link
 * #invoke()} method.
 */
public abstract class CancelableInvokable extends AbstractInvokable {

    private volatile boolean canceled;

    private final CompletableFuture<Void> terminationFuture = new CompletableFuture<>();

    protected CancelableInvokable(Environment environment) {
        super(environment);
    }

    @Override
    public void invoke() throws Exception {
        try {
            doInvoke();
            terminationFuture.complete(null);
        } catch (Exception e) {
            terminationFuture.completeExceptionally(e);
            throw e;
        }
    }

    protected abstract void doInvoke() throws Exception;

    @Override
    public Future<Void> cancel() {
        canceled = true;
        return terminationFuture;
    }

    protected void waitUntilCancelled() throws InterruptedException {
        synchronized (this) {
            while (!canceled) {
                wait();
            }
        }
    }
}
